The usage of overhead projection software is well established for liturgical and secular applications. In both liturgical usage and secular usage certain problems exist, some solutions of which I will discuss in regard to liturgical uses, whereas it should be understood that the same principles also apply just as well to secular uses.
There have been in the usage of overhead software problems relating to the timely display of portions of a lyric (and the same problems would apply to musical notation). Such problems relate to the fact that the person(s) running some overhead software often does not know what portion to display until the performance of said portion has already begun. This results in the congregation either mumbling, singing the wrong words or not at all during the first line of each new verse, since the projection comes late with the words. Even after the projectionist knows what portion is being sung, he or she must then locate and load the correct slide for such portion, which in itself takes additional time.